KEY FACTS
Terminology
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Abnormal direct communication between artery and vein
Imaging
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Usually in renal parenchyma; may be extrarenal
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Not usually visible when small
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Large arteriovenous fistulas: Dilated serpiginous vessels
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Feeding artery shows high-velocity, low-resistance waveform with spectral broadening
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Pulsatile arterialized flow in draining vein when large
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Perivascular tissue vibration producing color in adjacent tissues on color Doppler
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Catheter angiography is gold standard for diagnosis, allows endovascular treatment
Top Differential Diagnoses
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Pseudoaneurysm
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Renal artery stenosis
Pathology
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Complication of percutaneous transplant biopsy or insertion of nephrostomy
Clinical Issues
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Postbiopsy incidence: 1-18%
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Most asymptomatic or present with hematuria
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50% disappear within 48 hours; 70% resolve spontaneously within 1-2 years
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30% symptomatic and persistent
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Observation in majority with serial ultrasound
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Treated with superselective embolization of feeding artery if hematuria persists or renal function impaired
Scanning Tips
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Look for arteriovenous fistula when patients develop hematuria after renal transplant biopsy
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Best detected when background normal color flow is suppressed by using higher Doppler scale
